Numerous wheel sensors are available for sensing the ambient temperature and/or pressures in the ambient pneumatic region of a tyre.
GB2236885 employs an optical sensor in the context of wheel sensing. However, the optical sensor for receiving radiation is located in this prior art document on a stationary part of an associated hub assembly. The component associated with the rim is only an emitter. The combination of infra-red emitter and a sensor operates between the rim of the wheel and the stationary portion of the hub assembly. The optical sensor only receives data once every revolution when the emitter and sensor are in line. The optical sensor neither points towards the inside surface of the tyre nor does it view the inside surface in order to be able to receive radiation radiated from the inside surface.
The following further prior art documents are acknowledged: GB2363463, U.S. Pat. No. 5,708,411, and U.S. Pat. No. 5,663,496.
One object of the invention is to provide a wheel sensor which allows not only the ambient temperature to be measured, but also the surface temperature and in particular, the internal surface temperature of the tyre.
Another object of the invention is to improve the facility to assess the tyre condition during a motor race.
A further object of the invention is to provide a wheel sensor which may be readily integrated with other sensor features such as ambient pressure, and the temperature at the rim.
It is an object of the invention to provide a system which allows data to be gathered which is more closely linked to the evolution of temperature at the tyre surface and which would be less influenced by the rim temperature which is influenced by the heat generated during the braking process.
A further object of the invention is to provide a system which may be readily fitted to a rim without requiring specific rim and/or tyre modifications.
A further object of the invention is to allow a plurality of areas to be assessed independently around the wheel.